Re: [ATM] flex rocker question

[Dave Smith <smithersscope@yahoo.com>]

Hmm. Simple math can be challenging for me sometimes.
I know the mirror is 15 lb (good call). I also know 5
x 5 lb lead bricks is 25 lb lead (unless, of course I
only have 4 digits on my left hand?). I know my
endring is 7 lb fully fitted out. Truss tubes are
about 4 lb. and the mirror box is about 6 lb.

25 lb lead
15 lb mirror
6 lb mirror box
7 lb endring w/ finderscope
4 lb of truss tubes
____
55 lb OTA

Ooops, I'm off 10 lb.?!
It sure doesn't seem like 55 lb when I pick it up and
move it. I'll have to go weigh stuff again (and write
it down)...Just doesn't seem that heavy. ? ?

I think the flex rocker is less than 2 lb and the
ground ring is about 7 lb. But they don't count
towards the OTA weight.

I'll try to get the pics to you soon...headed out of
town this evening.

Dave

--- matt <marius_rf@bellsouth.net> wrote:

> Hi Dave,
> 
> Please email me those pics too if possible (no
> connection limitations) . I'm
> interested in lightweight flex rocker scopes , I'm
> building one myself .
> 
> I also have a question related to your scope weight,
> I understood you said
> 45 lbs with the 25lbs lead counterweight , which
> would mean 20 lbs left for
> the scope .
> The 16" diameter 1" thin mirror you're using should
> weigh around 15 lbs,
> which leaves 5 lbs for the rest of the scope , not
> quite possible .
> Therefore, it appears I misunderstood which
> components are and which are not
> included in the 45 lbs weight , please clarify .
> Even if worst case scenario the 45 lbs is without
> mirror and without
> counterweights, it would still be a lightweight
> scope and very interesting
> to see .
> 
> thank you,
> matt tudor
> 
> 
> -----Original Message-----
> From: Dave Smith <smithersscope@yahoo.com>
> To: Rod Brackenridge <rjbr@lycos.com>;
> atm@atmlist.net <atm@atmlist.net>
> Date: Friday, June 24, 2005 1:55 PM
> Subject: Re: [ATM] flex rocker question
> 
> 
> >Hi Rod,
> >I still haven't gotten my website back up, but I
> could
> >send you some pics if you're interested. (And let
> me
> >know what your connection speed is--I can adjust
> the
> >pics accordingly.) My setup is based almost
> entirely
> >on Mel's tri-dob design.
> >
> >To answer your questions:
> >Yes, the alt. bearings extend below the mirror box.
> >This gets the mirror as close to the ground as
> >possible and thus the focuser/eyepiece as low as
> >possible.
> >Mirror storage: Well, once I fold up the mirror
> box,
> >it will NOT sit in the bearings in the flex rocker
> >(but I can store it flat if I place it down inside
> the
> >ground ring and flex rocker base.) It actually
> slips
> >right on down to the floor. Like Mel's, the mirror
> box
> >(when collapsed) will actually stand up on the
> bottom
> >edge and is pretty stable in that position. But I'm
> >paranoid, so I usually store it nested in the
> ground
> >ring/flex rocker. This puts the altitude fin
> directly
> >on the ground (carpet), but I haven't noticed any
> >adverse effects on the bearing. Ebony Star is tough
> >stuff.
> >
> >A word of caution about the low position of the
> alt.
> >bearings in the tri-dob...the center of gravity is
> so
> >low that you'll likely have to add weight and/or
> Tom
> >Krajci's spring-based virtual counterbalance system
> to
> >counter a top heavy OTA and/or a thin mirror. I had
> to
> >add both (25 lb of lead....arrrggghhh!), but it is
> >working really well. My 16" f5.6, 1" thick plate
> >mirror scope weighs in at about 45 pounds (with the
> >lead butt) and I can easily set it up by myself.
> >
> >I'd be glad to try to answer any questions you have
> >though my experience is limited to this one scope.
> >Fire away!
> >
> >Dave
> >
> >--- Rod Brackenridge <rjbr@lycos.com> wrote:
> >
> >> Hi,
> >>
> >> I would like to build a flex rocker for a 12 inch
> F5
> >> newtonian.  I have been looking at some photos on
> >> the net to get some idea of what is involved.  My
> >> questions are:
> >>
> >> It looks like the altitude bearings in most
> designs
> >> extend below the mirror box.  Is this essential?
> >>
> >> Having them go below the rocker would seem to
> >> necessitate always storing the mirror box in the
> >> flex rocker and ring.  Is that how most of you do
> >> it?
> >>
> >> Thanks,
> >>
> >> Rod Brackenridge
> >> Mount Martha
> >> AUSTRALIA
> >>
> >> --
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> 
> 


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